How much ET will i pickup with following changes

It hooked all the time, no issues spinning. Car sits down over the tires because its minitubbed and has ladder bars. Yes, the convertor flashed at 4500.
I have tried leaving all over the place rpm wise. Doesnt effect how it 60 foots( and it shouldnt)
My old 9 sec Duster would 60 foot the same off idle or 2000 rpm off the foot, or 4400 using trans brake and two step.
I leave at 2k because its easier to look at the tach needle at 2000 for repeatability, keep it simple.
interesting. A little story here, I first learned to use a new j model convertor in my hemi belvedere at St. louis one year. There was a 70 hemi barracuda in my class, I was about 4 thenths faster than him in all the time trials. Class elim. came around, he staged and stalled so high I COULD HEAR HIM, I was holding about 2500, we cut the same light, and he jumped out about 4 car lengths on me , I caught him at the finish line and thot I had beat him, but the win light came on in his lane. We ran the same identicle E T, and I was "4 full mph faster" than him , but he won !